Process for separating mixtures of isomeric vat dyestuffs of the 1.4.5.8-naphthoylene diarylimidazole series into their components and the dyestuffs obtained thereby



Patented Aug. 20, 1935 PATENTXOFFEE PROCESS FOR SEPARATING MIXTURES OF ISOMERIC VAT DYESTUFFS OF THE 1.4.5.8 NAPHTHOYLENE DIARYLIMIDAZOLE SE- RIES INTO THEIR COMPONENTS AND THE DYESTUFFS OBTAINED THEREBY Wilhelm Eckertand Walter Gmelin, Frankforton-the-Main-Hochst, Germany, assignors to General Aniline Works, Inc., New York, N. Y., a corporation of Delaware No Drawing. Application April 29, 1933, Serial No; 668,664. In Germany May 4, 1932 1 8' Claims. (Cl. 260-44) The present invention relates to a process of separating mixtures of isomeric vat dyestuffs of the 1.4.5.8-naphthoylene diarylimidazole series into their components and to the dyestuffs obtained thereby. 7

We have found that mixtures of isomeric v'at dyestuffs which are obtainable by condensing a 1.4.5.8-naphthalene tetracarboxylic acid compound with an ortho-diami'no-compound andwhich have the general formula:

wherein the two Xs jointly represent the bivalent group and R means a n arylene radical bound to the nitrogen atoms in ortho-positionsmay be Separated very easily and with a good yield into their components by treating them in the presence or absence of an inert solvent ora suspension agent with a suitable metal chloride and separating from each other the new derivatives thus formed which may be addition compounds or'perhaps complex compounds, by taking advantage of their.

different solubilities. After the separation, the components may be converted into the dyestuffs proper by treatment with water or dilute mineral acids. As solvents there may be used, for instance,

' glacial acetic acid, nitrobenzene or the like and as suitable metal salts there may be used zinc chloride, aluminium chloride; tin tetra-chloride, antimony tri-chloride, antimony penta-chloride or the like.

small quantity of nitrobenzene.

The following examples serve to illustrate the invention' but they arenot limited thereto, the parts being by weight, unless otherwise stated? (1) 5 parts of the mixture of isomeric dyestuffs obtainable bycondensation of 1.4.5.8-naphthalene-tetra -carboxylic acid with ortho-phenylenediamine, for instance, by heating the two substances in nitrobenzene, are stirred at about C. toabout C. for 2-3 hours with 7 parts of aluminium chloride in 50 parts of dry nitrobenzene. There are soon formed the brown-yel1ow addition compounds of the isomeric dyestuffs with aluminium chloride one of which separates in the form of crystals whilst the other dissolves. After cooling to 10 C., the whole is filtered with suction and the solid matter is washed with a v The mass remaining on the filter is then stirred with alcohol whereby the, greater part of the addition compound is decomposed. The whole is filtered with suction and, in order to complete the decomposition, the solid matter is washed with dilute hy-.

. drochloric acid and then with water and dried.

The dyestuii thus obtained dyes cotton from a dark green vat orange tints.

From the nitrobenzene-filtrate the isomeric dyestuff is obtained by removing the nitrobenzene by distillation with steam and adding a small quantity of hydrochloric acid, in order to entirely split off the aluminium chloride; the whole is filtered with suction and the solidmatter is washed until neutral and dried. The dyestuff thus obtained dyes cotton'blui'sh-red tints.

(2) loparts of the dyestuii mixture of isomeric 1.4 .5 .8 naphthoylenel' .5 .4 .5 tetrachloro-di-' phenylimidazoles, obtainable, for instance, by condensation of :1.4.5.8-naphthalene-tetracarboxylic acid or-the anhydride thereof with 1.2- diamino-4.5 dichlorobenzene, are suspended in about parts by volume of dry nitrobenzene and about l3'parts of tin, tetra-chloride are added thereto. The whole is heated for 2-3 hours at 50 C. to 60 C., allowed to cool and the difiicultly soluble addition product of the one isomeric dyestuif with tin tetra-chloride which has been formed is filteredwith suction, washed with a small quantity of nitro-benzene and then with alcohol. Byintrod-ucing this addition product or the complex compound; respectively, into water or a dilute mineral acid, it is hydrolyzed whereby the dyestuff of the following probable formula is obtained:

. $1. a It formsan orange-red powder which dissolves in concentrated sulfuric acid toa yellow-red solution and dyes the vegetable .fiber from an olive green vat very clear orange tints of very good fastness properties. v v 4 In order to obtain the isomeric dyestufi:

wherein the two Xs jointly represent the bivalent group I K N and may be obtained by condensation of 1.4.5.8- naphthalene-tetracarboxylio acid, or the anhydride thereof, iwi-t-h 2J3-diamino-to1uene are suspended in about 1'80 parts by volume of dry nitrobenzene; about 25 parts of antimony trichlorideare added and the whole is heated at 70 C. to C. for some hours. After the 'iiorinaition o'f the respective feebly-brown addiproducts; the whole is allowed to cool and the product is worked up as described in Example 2.' Thedyestuff which may be obtained by hydrolysis fromtlie-difiicultly soluble addition product dyes the vegetable fiber from an olive-green vat very clear yellowish scarlet tints. The dyestuii obtainable from the easily-sdlub1e addition product "i n th e filtrate dyes the vegetable fiber Bordeauxtints.

We'dl'aim: H H w I 1. The process which comprises treating a mixture 'of isomeric dyestuffs of 'the general formula:

R v i 0o 0 X v X wherein the two Xs jointly represent the bivalent group:

with/aluminium chlorideiin-lthepresence of nitrm wherein the two-X?sjoint1y representthe bivalent group and R. means an arylene radical of the benzene series bound to the nitrogen atoms in orthopositions, with a metall'chloride of the group consisting of zinc chloride, antimony pentachlov ride, antimony trichloride, .aluminium chloride and tin tetra-chloride in the presence of an inert organic'diluent and separating the mixture of isomeric compounds thus obtained into its components by taking advantage of their different solubilities.

3. The process which comprises heating for some hours at a temperature of about50 C. to about C. a mixture ofisomeric dyestuffs of the .generaliformula' wherein the two Xs jointly represent the bivalent group: i

wherein the two X's jointly represent the bivalent group:

a t vs mixture of two isomeric dyes-tuifs of the formula:

ime;

jecting the above solution of the other addition compound to asteam-distillation, in order to remove the nitrobenzene, and to a treatment with dilute hydrochloric acid.

6. The compounds of the following formula;

wherein the two X's jointly represent the bivalent group Oi t and the CHa-group stands in one of the positions dyeing the vegetable fiber from a green vat Wher e weIs i rep ent hebivaleni I 11:33! eom'poumiofi the'iotmulat r yellowish scarlet aminm'gieaux 1. Thecompoundot thBt-IWL i..

wherein the CHz-group stands inone'aofithe-positions dyeing the vegetable fiber from an olive green vat very clear yellowish scarlet; tints.

' WILHELM ECKERT.

WQLTER GMELIN.

wherein the dfli-greup standsiirr one (if-the tions dyeing the vegetable fiber from a green: vat Bordeaux tints. 

